The direct measurement of the optical power levels of a series of DWDM channels is typically performed in either a serial manner, using a tunable filter and a single OCM device, or in a parallel manner, using a 1×N filter and multiple OCM devices, where N is the number of DWDM channels. When measuring the optical power levels of multiple series of DWDM channels traveling on separate optical fibers, either multiple OCM devices are used, one for each optical fiber, or an N×1 selection switch and a single OCM device are used, where N is the number of optical fibers, and where the OCM device alternates between measuring the optical power levels of each of the series of DWDM channels.
When measuring the optical power levels of multiple series of DWDM channels traveling on separate optical fibers using multiple OCM devices, the cost is typically excessive, as each OCM device is relatively expensive. This cost can be reduced by using the N×1 selection switch and a single OCM device, as the cost of the N×1 selection switch is currently much less than the cost of an additional OCM device. The significant drawback of this configuration and procedure, however, is that the frequency at which optical power level measurements can be made is limited by the switch rate of the N×1 selection switch, the switch rate of the N×1 selection switch being considerably slower than the rate at which the OCM device can complete the optical power level measurements of all of the DWDM channels in a series. For example, a 1×N filter and multiple OCM devices can complete the optical power level measurements of all of the DWDM channels in a series at a rate approaching about 1 MHz. The average switch rate of an N×1 selection switch is less than about 100 Hz. Therefore, the optical power levels of multiple series of DWDM channels traveling on separate optical fibers can only be measured at a rate of about 100 Hz, and the optical power levels of multiple series of DWDM channels cannot be measured simultaneously.
Thus, what is needed is a relatively inexpensive OCM assembly for simultaneously measuring the optical power levels of multiple series of DWDM channels or the like traveling on separate optical fibers in an optical communications system.